Field of the Invention
The present invention relates to temporarily storing carriers to house semiconductor wafers or the like.
Description of the Related Art
In order to improve the utilisation rate of semiconductor fabrication equipment, temporal storage apparatuses (buffers) are provided in the vicinity of load ports of semiconductor fabrication equipment. In this regard, Patent Literature 1 (JP 2012-111635) by the applicant has proposed to provide a travelling rail for a local vehicle in parallel with and below a travelling rail for overhead travelling vehicles (overhead hoist transports (OHT)). If buffers usable for both the local vehicle and the overhead travelling vehicles are provided at positions below the travelling rail for the local vehicle and not over the load ports, for example, four buffers may be provided. If further buffers are necessary, one design is to provide the overhead travelling vehicles and the local vehicle with a lateral transfer mechanism for carriers and to provide additional buffers at downward and sideways positions from the travelling rail for the local vehicle.